The most popular protein powders are the ones derived from cow’s milk: whole milk, casein and whey protein. The whole-milk protein powders have lactose and fat filtrated out of it, while keeping casein and whey (the ratio of 80 % casein and 20 % whey) intact. The full digestion of casein takes up to 5-7 hours, which means that you get a slow and steady amino acid release for the extensive period of time. Whey protein is the opposite of casein – its digestion and absorption is very quick. That makes whey protein powders useful for taking before and after weight training sessions when it is critical to supply muscles with amino acids. In contrast casein, with its slow digestion, is great to feed your body at sleep and prevent muscle breakdown during the night time (especially when you are on calorie restricted diet). The variations of milk derived protein powders:
• Milk concentrate protein – normally contains around 80 % of protein, 5-10 % lactose, low fat.
• Milk protein isolate – has 90% of protein and very little lactose or/and fat.
• Caseinate – higher than 90 % of casein with added calcium, sodium or potassium.
• Micellar casein – due to its low temperature obtaining process of the casein, this is the slowest digesting protein – the best choice for the night-time.
• Hydrolysed casein – due to broken bonds between amino acids this is the fastest digested and absorbed casein protein, most suitable for pre and post workouts like the whey protein.
• Whey protein concentrate – contains 70-80 % of protein, leaving 20-30 % to carbs and fat which makes it the slowest digested and absorbed whey protein.
• Whey protein isolate – protein is 90 % or higher, however processing techniques can remove some of the useful protein fractions.
• Whey protein hydrolysate – produced via hydrolysis of whey protein concentrate or whey protein isolate to break the amino acid bonds, which makes it the fastest digesting whey protein. The negative is that it can taste slightly bitter.
Egg protein powders are great for pre and post training supplementation, as it has very high percent of protein, reaching virtually 100 % and its digestion/absorption is very fast. Also, egg-white protein is high in amino acids that contain sulphur – they play an important role in hormone production. Nowadays many egg protein powders have got rid of avidin, which is a glycoprotein in egg whites that depletes the body of biotin (a vitamin that is important for the overall wellbeing and the metabolism of fats, proteins and carbohydrates).
Soy protein powders are high in glutamine and arginine as well as contain all 8 essential amino acids. Also, soy protein provides antioxidant effects and it is quickly digested/absorbed (good for pre and post workouts). Many bodybuilders are concerned that soy protein is high in isoflavones (the organic compounds that are capable of exerting oestrogen-like effects), however there is no substantial scientific evidence that the isoflavones oppose the anabolic effects of testosterone. The variations of soy protein:
• Soy protein concentrate – usually has around 70 % of protein, the rest being carbs and fat. Soy concentrate often contains indigestible carbs causing gas.
• Soy protein isolate – higher than 90 % of protein and no gas issues. Faster digesting/absorbing than the soy concentrate.
Goat’s milk protein powders contain about 65 % of protein – the rest comes from carbs and fat. Goat’s whey protein powders have only 15-20 % of protein and a lot of carbs therefore it cannot equal the amino acid supply of the cow’s milk whey protein powders. However goat’s milk protein has lots of minerals which is very beneficial for the optimal health.